蓄水后向家坝库区鱼类物种、分类和功能多样性变化OACSTPCD

The impacts of the construction of hydropower projects on fish are of particular concern.To understand its effects on fish diversity from the Xiangjiaba Reservoir in the lower Jinsha River,quantitative surveys were conducted for the spatial distribution of taxonomic and functional diversity of fish assemblages in Shaonvping,Suijiang and Huixi sections,located in the lower,middle and upper streams of the reservoir,respectively,during 2016-2018.Combined with the data before(2011)and at the beginning(2015)of impoundment,the change in fish diversity in different dimensions in the lower reaches of the Jinsha River due to im-poundment was discussed.Eurytopic and limnophilic fish species such as Pseudobagrus vachelli and Hemiculter leucisculus domina-ted the Xiangjiaba Reservoir.P.vachelli and H.leucisculus accounted for 30.15％±14.82％and 13.91％±11.16％in abundance,respectively.Nonmetric multidimensional scaling showed that the fish community structure was more similar between Shaonvping and Suijiang sections.In contrast,fish community differed from Shaonvping and Huixi sections.In Suijiang section,fish communi-ties in the three periods(before,during and after the impoundment)were significantly different,indicating that fish communities in Suijiang section have undergone dramatic changes after the impoundment.Higher values of Margalef index,Shannon-Wiener in-dex and Pielou index of fish in different river sections of the reservoir area were shown as follows:Huixi＞Shaonvping＞Suijiang;Taxonomic diversity index and taxonomic differencess index were shown as follows:Huixi＞Suijiang＞Shaonvping.The spatial pat-tern of functional diversity(functional richness,functional evenness and functional divergence)in different dimensions of fish feeding,movement and reproduction in the reservoir area was different.Generally,the highest functional richness and the lowest functional evenness were found in Suijiang Section.The species and taxonomic diversity in Suijiang section showed a decreased trend compared with that before impoundment.The functional richness and evenness also showed a decreased trend.Functional traits of different dimensions,such as feeding,movement and reproduction,had significant changes after impoundment.For exam-ple,the dominant fishes changed from the species with inferior position mouth and fusiform body shape to those with terminal posi-tion mouth and compressiform body shape.Different diversity indices focus on different aspects of fish diversity.The combination of multiple index analysis is conducive to a more comprehensive understanding of the response of fish communities to environmental changes and external disturbances.This study improved our understanding on the effects of hydropower projects on fish diversity in the lower Jinsha River,provided a scientific basis for fish conservation,and surveyed data for ecological effect assessment of Ten-Year fishing Ban.